The present invention relates to a rotary actuator for operating and/or driving a surface, such as a wing flap, rudder, or door in an aircraft. More specifically, it relates to a rotary helical hinge actuator which may consist of a single module or may employ multiple modules. Still further, the invention relates to a rotary helical hinge actuator using helical gear teeth in a balanced, multiple spindle gear arrangment in order to produce a maximum torque in a minimum space. This is particularly useful in operating a flap panel on a high speed airplane with thin wings, where the actuator provides torque to drive the flap panel as well as bearing support which transmits any shear loads back to the main structure of the plane.